Cooling liquid has to be replaced at repair of the cooling system at which liquid merges. In case at repair the head of cylinders, the block of cylinders, sealing laying of a head of cylinders, a radiator, the heat exchanger or the engine are replaced, then cooling liquid has to be replaced with new. In the course of circulation anticorrosive additives are besieged on new details from light metal and by that form a durable anticorrosive layer. In the used cooling liquid of anticorrosive additive, as a rule, it is already not enough to form a sufficient protective layer on new details.